Flameless catalytic fragrance lamps that auto-catalytically burn a fragrance/fuel mixture to emit a fragrance have been available for over 100 years. The typical fragrance lamps burn fuel that is composed of approximately 90 wt % 2-propanol, 8 wt % water, and 2 wt % fragrance. Currently, there are several flameless catalytic lamps available on the market. The catalytic fragrance lamps currently employ low boiling alcohol-based fuel for several reasons. The fuel is used as a carrier for the fragrance. The fragrance/alcohol mixture is transported from a reservoir to a flameless catalytic burner which simultaneously combusts the alcohol while dispersing the fragrance in the surrounding atmosphere. Alcohols are also used because their high vapor pressure (2-propanol has a vapor pressure of 42.74 mm Hg at 25° C.) allows them to soak the wick, which transports them to the burner very efficiently and allows a sufficient, continual flow of fuel from the reservoir to the catalytic burner. Furthermore, combustion of low boiling alcohols by the catalytic burner produces only small amounts of carbon, or coke, which over several months of intermittent use will cause the catalytic burner to clog and cease operation. Finally, catalytic combustion of 2-propanol produces almost no smoke, so the fragrance is released while not producing any visible smoke from the catalytic fragrance lamps.
However, currently used fuel mixtures will likely face severe use restrictions in the future by regulatory bodies seeking to minimize pollution. The California Air Resources Board (CARB) plans to impose bans on currently used fuel mixtures that contain greater than 18 wt % of alcohol-based fuels. As an example, 2-propanol is classified as a volatile organic compound (VOC), and currently used fuel mixtures contain greater than 18 wt % of 2-propanol relative to the total composition.
In light of the environmental and pollution concerns surrounding currently used fuel mixtures, it is desirable to develop new fuel compositions for use in catalytic fragrance lamps that meet or exceed VOC regulations imposed by regulatory bodies such as CARB. The present invention is directed to the identification and formulation of compounds that will meet the above mentioned requirements and function as suitable fuels for catalytic fragrance lamps.